Merge tag 'kraxel-20220704-pull-request' of https://gitlab.com/kraxel/qemu into staging
[qemu.git] / net / netmap.c
1 /*
2 * netmap access for qemu
3 *
4 * Copyright (c) 2012-2013 Luigi Rizzo
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25
26 #include "qemu/osdep.h"
27 #include <sys/ioctl.h>
28 #include <net/if.h>
29 #define NETMAP_WITH_LIBS
30 #include <net/netmap.h>
31 #include <net/netmap_user.h>
32
33 #include "net/net.h"
34 #include "net/tap.h"
35 #include "clients.h"
36 #include "qemu/error-report.h"
37 #include "qapi/error.h"
38 #include "qemu/iov.h"
39 #include "qemu/cutils.h"
40 #include "qemu/main-loop.h"
41
42 typedef struct NetmapState {
43 NetClientState nc;
44 struct nm_desc *nmd;
45 char ifname[IFNAMSIZ];
46 struct netmap_ring *tx;
47 struct netmap_ring *rx;
48 bool read_poll;
49 bool write_poll;
50 struct iovec iov[IOV_MAX];
51 int vnet_hdr_len; /* Current virtio-net header length. */
52 } NetmapState;
53
54 #ifndef __FreeBSD__
55 #define pkt_copy bcopy
56 #else
57 /* A fast copy routine only for multiples of 64 bytes, non overlapped. */
58 static inline void
59 pkt_copy(const void *_src, void *_dst, int l)
60 {
61 const uint64_t *src = _src;
62 uint64_t *dst = _dst;
63 if (unlikely(l >= 1024)) {
64 bcopy(src, dst, l);
65 return;
66 }
67 for (; l > 0; l -= 64) {
68 *dst++ = *src++;
69 *dst++ = *src++;
70 *dst++ = *src++;
71 *dst++ = *src++;
72 *dst++ = *src++;
73 *dst++ = *src++;
74 *dst++ = *src++;
75 *dst++ = *src++;
76 }
77 }
78 #endif /* __FreeBSD__ */
79
80 /*
81 * Open a netmap device. We assume there is only one queue
82 * (which is the case for the VALE bridge).
83 */
84 static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
85 Error **errp)
86 {
87 struct nm_desc *nmd;
88 struct nmreq req;
89
90 memset(&req, 0, sizeof(req));
91
92 nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
93 NULL);
94 if (nmd == NULL) {
95 error_setg_errno(errp, errno, "Failed to nm_open() %s",
96 nm_opts->ifname);
97 return NULL;
98 }
99
100 return nmd;
101 }
102
103 static void netmap_send(void *opaque);
104 static void netmap_writable(void *opaque);
105
106 /* Set the event-loop handlers for the netmap backend. */
107 static void netmap_update_fd_handler(NetmapState *s)
108 {
109 qemu_set_fd_handler(s->nmd->fd,
110 s->read_poll ? netmap_send : NULL,
111 s->write_poll ? netmap_writable : NULL,
112 s);
113 }
114
115 /* Update the read handler. */
116 static void netmap_read_poll(NetmapState *s, bool enable)
117 {
118 if (s->read_poll != enable) { /* Do nothing if not changed. */
119 s->read_poll = enable;
120 netmap_update_fd_handler(s);
121 }
122 }
123
124 /* Update the write handler. */
125 static void netmap_write_poll(NetmapState *s, bool enable)
126 {
127 if (s->write_poll != enable) {
128 s->write_poll = enable;
129 netmap_update_fd_handler(s);
130 }
131 }
132
133 static void netmap_poll(NetClientState *nc, bool enable)
134 {
135 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
136
137 if (s->read_poll != enable || s->write_poll != enable) {
138 s->write_poll = enable;
139 s->read_poll = enable;
140 netmap_update_fd_handler(s);
141 }
142 }
143
144 /*
145 * The fd_write() callback, invoked if the fd is marked as
146 * writable after a poll. Unregister the handler and flush any
147 * buffered packets.
148 */
149 static void netmap_writable(void *opaque)
150 {
151 NetmapState *s = opaque;
152
153 netmap_write_poll(s, false);
154 qemu_flush_queued_packets(&s->nc);
155 }
156
157 static ssize_t netmap_receive_iov(NetClientState *nc,
158 const struct iovec *iov, int iovcnt)
159 {
160 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
161 struct netmap_ring *ring = s->tx;
162 unsigned int tail = ring->tail;
163 ssize_t totlen = 0;
164 uint32_t last;
165 uint32_t idx;
166 uint8_t *dst;
167 int j;
168 uint32_t i;
169
170 last = i = ring->head;
171
172 if (nm_ring_space(ring) < iovcnt) {
173 /* Not enough netmap slots. Tell the kernel that we have seen the new
174 * available slots (so that it notifies us again when it has more
175 * ones), but without publishing any new slots to be processed
176 * (e.g., we don't advance ring->head). */
177 ring->cur = tail;
178 netmap_write_poll(s, true);
179 return 0;
180 }
181
182 for (j = 0; j < iovcnt; j++) {
183 int iov_frag_size = iov[j].iov_len;
184 int offset = 0;
185 int nm_frag_size;
186
187 totlen += iov_frag_size;
188
189 /* Split each iovec fragment over more netmap slots, if
190 necessary. */
191 while (iov_frag_size) {
192 nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
193
194 if (unlikely(i == tail)) {
195 /* We ran out of netmap slots while splitting the
196 iovec fragments. */
197 ring->cur = tail;
198 netmap_write_poll(s, true);
199 return 0;
200 }
201
202 idx = ring->slot[i].buf_idx;
203 dst = (uint8_t *)NETMAP_BUF(ring, idx);
204
205 ring->slot[i].len = nm_frag_size;
206 ring->slot[i].flags = NS_MOREFRAG;
207 pkt_copy(iov[j].iov_base + offset, dst, nm_frag_size);
208
209 last = i;
210 i = nm_ring_next(ring, i);
211
212 offset += nm_frag_size;
213 iov_frag_size -= nm_frag_size;
214 }
215 }
216 /* The last slot must not have NS_MOREFRAG set. */
217 ring->slot[last].flags &= ~NS_MOREFRAG;
218
219 /* Now update ring->head and ring->cur to publish the new slots and
220 * the new wakeup point. */
221 ring->head = ring->cur = i;
222
223 ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
224
225 return totlen;
226 }
227
228 static ssize_t netmap_receive(NetClientState *nc,
229 const uint8_t *buf, size_t size)
230 {
231 struct iovec iov;
232
233 iov.iov_base = (void *)buf;
234 iov.iov_len = size;
235
236 return netmap_receive_iov(nc, &iov, 1);
237 }
238
239 /* Complete a previous send (backend --> guest) and enable the
240 fd_read callback. */
241 static void netmap_send_completed(NetClientState *nc, ssize_t len)
242 {
243 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
244
245 netmap_read_poll(s, true);
246 }
247
248 static void netmap_send(void *opaque)
249 {
250 NetmapState *s = opaque;
251 struct netmap_ring *ring = s->rx;
252 unsigned int tail = ring->tail;
253
254 /* Keep sending while there are available slots in the netmap
255 RX ring and the forwarding path towards the peer is open. */
256 while (ring->head != tail) {
257 uint32_t i = ring->head;
258 uint32_t idx;
259 bool morefrag;
260 int iovcnt = 0;
261 int iovsize;
262
263 /* Get a (possibly multi-slot) packet. */
264 do {
265 idx = ring->slot[i].buf_idx;
266 morefrag = (ring->slot[i].flags & NS_MOREFRAG);
267 s->iov[iovcnt].iov_base = (void *)NETMAP_BUF(ring, idx);
268 s->iov[iovcnt].iov_len = ring->slot[i].len;
269 iovcnt++;
270 i = nm_ring_next(ring, i);
271 } while (i != tail && morefrag);
272
273 /* Advance ring->cur to tell the kernel that we have seen the slots. */
274 ring->cur = i;
275
276 if (unlikely(morefrag)) {
277 /* This is a truncated packet, so we can stop without releasing the
278 * incomplete slots by updating ring->head. We will hopefully
279 * re-read the complete packet the next time we are called. */
280 break;
281 }
282
283 iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt,
284 netmap_send_completed);
285
286 /* Release the slots to the kernel. */
287 ring->head = i;
288
289 if (iovsize == 0) {
290 /* The peer does not receive anymore. Packet is queued, stop
291 * reading from the backend until netmap_send_completed(). */
292 netmap_read_poll(s, false);
293 break;
294 }
295 }
296 }
297
298 /* Flush and close. */
299 static void netmap_cleanup(NetClientState *nc)
300 {
301 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
302
303 qemu_purge_queued_packets(nc);
304
305 netmap_poll(nc, false);
306 nm_close(s->nmd);
307 s->nmd = NULL;
308 }
309
310 /* Offloading manipulation support callbacks. */
311 static int netmap_fd_set_vnet_hdr_len(NetmapState *s, int len)
312 {
313 struct nmreq req;
314
315 /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header
316 * length for the netmap adapter associated to 's->ifname'.
317 */
318 memset(&req, 0, sizeof(req));
319 pstrcpy(req.nr_name, sizeof(req.nr_name), s->ifname);
320 req.nr_version = NETMAP_API;
321 req.nr_cmd = NETMAP_BDG_VNET_HDR;
322 req.nr_arg1 = len;
323
324 return ioctl(s->nmd->fd, NIOCREGIF, &req);
325 }
326
327 static bool netmap_has_vnet_hdr_len(NetClientState *nc, int len)
328 {
329 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
330 int prev_len = s->vnet_hdr_len;
331
332 /* Check that we can set the new length. */
333 if (netmap_fd_set_vnet_hdr_len(s, len)) {
334 return false;
335 }
336
337 /* Restore the previous length. */
338 if (netmap_fd_set_vnet_hdr_len(s, prev_len)) {
339 error_report("Failed to restore vnet-hdr length %d on %s: %s",
340 prev_len, s->ifname, strerror(errno));
341 abort();
342 }
343
344 return true;
345 }
346
347 /* A netmap interface that supports virtio-net headers always
348 * supports UFO, so we use this callback also for the has_ufo hook. */
349 static bool netmap_has_vnet_hdr(NetClientState *nc)
350 {
351 return netmap_has_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
352 }
353
354 static void netmap_using_vnet_hdr(NetClientState *nc, bool enable)
355 {
356 }
357
358 static void netmap_set_vnet_hdr_len(NetClientState *nc, int len)
359 {
360 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
361 int err;
362
363 err = netmap_fd_set_vnet_hdr_len(s, len);
364 if (err) {
365 error_report("Unable to set vnet-hdr length %d on %s: %s",
366 len, s->ifname, strerror(errno));
367 } else {
368 /* Keep track of the current length. */
369 s->vnet_hdr_len = len;
370 }
371 }
372
373 static void netmap_set_offload(NetClientState *nc, int csum, int tso4, int tso6,
374 int ecn, int ufo)
375 {
376 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
377
378 /* Setting a virtio-net header length greater than zero automatically
379 * enables the offloadings. */
380 if (!s->vnet_hdr_len) {
381 netmap_set_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
382 }
383 }
384
385 /* NetClientInfo methods */
386 static NetClientInfo net_netmap_info = {
387 .type = NET_CLIENT_DRIVER_NETMAP,
388 .size = sizeof(NetmapState),
389 .receive = netmap_receive,
390 .receive_iov = netmap_receive_iov,
391 .poll = netmap_poll,
392 .cleanup = netmap_cleanup,
393 .has_ufo = netmap_has_vnet_hdr,
394 .has_vnet_hdr = netmap_has_vnet_hdr,
395 .has_vnet_hdr_len = netmap_has_vnet_hdr_len,
396 .using_vnet_hdr = netmap_using_vnet_hdr,
397 .set_offload = netmap_set_offload,
398 .set_vnet_hdr_len = netmap_set_vnet_hdr_len,
399 };
400
401 /* The exported init function
402 *
403 * ... -net netmap,ifname="..."
404 */
405 int net_init_netmap(const Netdev *netdev,
406 const char *name, NetClientState *peer, Error **errp)
407 {
408 const NetdevNetmapOptions *netmap_opts = &netdev->u.netmap;
409 struct nm_desc *nmd;
410 NetClientState *nc;
411 Error *err = NULL;
412 NetmapState *s;
413
414 nmd = netmap_open(netmap_opts, &err);
415 if (err) {
416 error_propagate(errp, err);
417 return -1;
418 }
419 /* Create the object. */
420 nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
421 s = DO_UPCAST(NetmapState, nc, nc);
422 s->nmd = nmd;
423 s->tx = NETMAP_TXRING(nmd->nifp, 0);
424 s->rx = NETMAP_RXRING(nmd->nifp, 0);
425 s->vnet_hdr_len = 0;
426 pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
427 netmap_read_poll(s, true); /* Initially only poll for reads. */
428
429 return 0;
430 }
431